Quentin has battled a bone bruise since he jammed his left knee while making a diving catch in the outfield on March 16. The injury followed a string of three surgeries on his right knee in the last two years -- including a season-ending operation last September.

Black said the doctors did not discover any ligament damage or anything else that might linger in Quentin's current ailment, but Black was not prepared to give a target return date for the 31-year-old slugger.

"No timeframe, but again this is an injury that will heal," Black said. "The pain will lessen; the bone will heal. It's just time [that he needs]."

In Nady, Black said he wanted a veteran presence on the bench -- both as a pinch-hitting option and as a fill-in at either of the corner outfield spots and first base.

That meant the final roster spot came down to Blanks and Medica. Blanks has the edge in big league experience, having played for the Padres in parts of five seasons, but, ultimately, the Padres opted for the 25-year-old Medica, who batted .333 with three homers and a .561 slugging percentage in 27 Spring Training games entering Saturday.

"It was a tough decision, no doubt about it," Black said. "We felt the way Tommy played this spring that he hit his way onto the team. He played well. What he did in September was a prelude to hopefully some things to come."

Medica, who made his big league debut last fall as a September callup, was understandably thrilled to be named to his first Opening Day roster.

And there is a chance Medica could be making his first Opening Day start, as well. Left-handed hitting outfielder Will Venable missed the Padres' two exhibition games against the Indians at Fowler Park this weekend because of some minor back trouble.

Venable will most likely be healthy enough to play Sunday night, but Black may opt for Medica in left field anyway, giving the Padres a righty-heavy lineup against Dodgers lefty Hyun-Jin Ryu.

"It's awesome," Medica said. "To be able to be on the team Opening Day -- it's a dream come true."

That is not to say Black's decision to include Medica came out of left field, but that is exactly where Black delivered the news to Medica at Petco Park.

Fitting perhaps, as Medica worked tirelessly this spring to learn the position. He was drafted as a catcher before transitioning to first base four years ago.

As for the 35-year-old Nady, his first at-bat this season will be his first big league appearance since finishing 2012 with the Giants. Nady spent last year between the Royals' and Rockies' Triple-A affiliates.

"Obviously, every year the goal is to make the big league ballclub when you're playing," Nady said. "It's been a grind the last couple of years. You go through times where there's injuries, or you're still playing at Triple-A to see if you still have it. I came in this spring, and all I wanted was an opportunity."

The Padres announced their full 12-man pitching staff Friday, leaving the bench as the only lingering roster question. Assuming full health among the starters on the active roster, Nady, Medica, Grandal, Rivera and Alexi Amarista will comprise that bench.

AJ Cassavell is a reporter for MLB.com Follow him on Twitter @ajcassavell. This story was not subject to the approval of Major League Baseball or its clubs.